Re: cpu temperature readings

[Michael van Elst <mlelstv%serpens.de@localhost>]

On Thu, Jun 29, 2023 at 12:03:33PM +0200, Rhialto wrote:
> On Thu 29 Jun 2023 at 16:50:27 +0700, Robert Elz wrote:
> > And then for fun, at 3401 ... this one I needed to run the test several
> > times until the kernel picked one of the fastest processors to run it on
> 
> When I was muddling with estd to dynamically slow down my cpus when not
> in use, I was told that the xx01 frequency on modern (Intel) processors
> will do that, even though in many sources that setting is still called
> "turbo boost" or similar. The other frequencies would actually be fixed.
> In your cpu this may be the case too, which would give confusing results
> if you're not aware of the possibility.


The xx01 frequency sets the maximum base clock and enables turbo mode...
on systems that support such a setting.

On "modern CPUs" however, it is often sufficient to stay on that setting
as "racing to completion" needs the least power. To some degree however
this assumes that the CPU enters a low-power idle mode when "complete",
so YMMV on NetBSD.

The Haswell CPU here (room temperature about 27C) runs idle at about 40C
when clocked at minimum 800, but heats up to 47C when idling at 3300 and
there is no difference to 3301.


Greetings,
-- 
                                Michael van Elst
Internet: mlelstv%serpens.de@localhost
                                "A potential Snark may lurk in every tree."